[PATCH] xtensa: Architecture support for Tensilica Xtensa Part 5

The attached patches provides part 5 of an architecture implementation for the
Tensilica Xtensa CPU series.

Signed-off-by: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 551 insertions, 0 deletions

diff --git a/arch/xtensa/mm/init.c b/arch/xtensa/mm/init.c
new file mode 100644
index 00000000000..56aace84aae
--- /dev/null
+++ b/arch/xtensa/mm/init.c
@@ -0,0 +1,551 @@
+/*
+ * arch/xtensa/mm/init.c
+ *
+ * Derived from MIPS, PPC.
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2001 - 2005 Tensilica Inc.
+ *
+ * Chris Zankel	<chris@zankel.net>
+ * Joe Taylor	<joe@tensilica.com, joetylr@yahoo.com>
+ * Marc Gauthier
+ * Kevin Chea
+ */
+
+#include <linux/config.h>
+#include <linux/init.h>
+#include <linux/signal.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/ptrace.h>
+#include <linux/bootmem.h>
+#include <linux/swap.h>
+
+#include <asm/pgtable.h>
+#include <asm/bootparam.h>
+#include <asm/mmu_context.h>
+#include <asm/tlb.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+#include <asm/pgalloc.h>
+#include <asm/pgtable.h>
+
+
+#define DEBUG 0
+
+DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+//static DEFINE_SPINLOCK(tlb_lock);
+
+/*
+ * This flag is used to indicate that the page was mapped and modified in
+ * kernel space, so the cache is probably dirty at that address.
+ * If cache aliasing is enabled and the page color mismatches, update_mmu_cache
+ * synchronizes the caches if this bit is set.
+ */
+
+#define PG_cache_clean PG_arch_1
+
+/* References to section boundaries */
+
+extern char _ftext, _etext, _fdata, _edata, _rodata_end;
+extern char __init_begin, __init_end;
+
+/*
+ * mem_reserve(start, end, must_exist)
+ *
+ * Reserve some memory from the memory pool.
+ *
+ * Parameters:
+ *  start	Start of region,
+ *  end		End of region,
+ *  must_exist	Must exist in memory pool.
+ *
+ * Returns:
+ *  0 (memory area couldn't be mapped)
+ * -1 (success)
+ */
+
+int __init mem_reserve(unsigned long start, unsigned long end, int must_exist)
+{
+	int i;
+
+	if (start == end)
+		return 0;
+
+	start = start & PAGE_MASK;
+	end = PAGE_ALIGN(end);
+
+	for (i = 0; i < sysmem.nr_banks; i++)
+		if (start < sysmem.bank[i].end
+		    && end >= sysmem.bank[i].start)
+			break;
+
+	if (i == sysmem.nr_banks) {
+		if (must_exist)
+			printk (KERN_WARNING "mem_reserve: [0x%0lx, 0x%0lx) "
+				"not in any region!\n", start, end);
+		return 0;
+	}
+
+	if (start > sysmem.bank[i].start) {
+		if (end < sysmem.bank[i].end) {
+			/* split entry */
+			if (sysmem.nr_banks >= SYSMEM_BANKS_MAX)
+				panic("meminfo overflow\n");
+			sysmem.bank[sysmem.nr_banks].start = end;
+			sysmem.bank[sysmem.nr_banks].end = sysmem.bank[i].end;
+			sysmem.nr_banks++;
+		}
+		sysmem.bank[i].end = start;
+	} else {
+		if (end < sysmem.bank[i].end)
+			sysmem.bank[i].start = end;
+		else {
+			/* remove entry */
+			sysmem.nr_banks--;
+			sysmem.bank[i].start = sysmem.bank[sysmem.nr_banks].start;
+			sysmem.bank[i].end   = sysmem.bank[sysmem.nr_banks].end;
+		}
+	}
+	return -1;
+}
+
+
+/*
+ * Initialize the bootmem system and give it all the memory we have available.
+ */
+
+void __init bootmem_init(void)
+{
+	unsigned long pfn;
+	unsigned long bootmap_start, bootmap_size;
+	int i;
+
+	max_low_pfn = max_pfn = 0;
+	min_low_pfn = ~0;
+
+	for (i=0; i < sysmem.nr_banks; i++) {
+		pfn = PAGE_ALIGN(sysmem.bank[i].start) >> PAGE_SHIFT;
+		if (pfn < min_low_pfn)
+			min_low_pfn = pfn;
+		pfn = PAGE_ALIGN(sysmem.bank[i].end - 1) >> PAGE_SHIFT;
+		if (pfn > max_pfn)
+			max_pfn = pfn;
+	}
+
+	if (min_low_pfn > max_pfn)
+		panic("No memory found!\n");
+
+	max_low_pfn = max_pfn < MAX_LOW_MEMORY >> PAGE_SHIFT ?
+		max_pfn : MAX_LOW_MEMORY >> PAGE_SHIFT;
+
+	/* Find an area to use for the bootmem bitmap. */
+
+	bootmap_size = bootmem_bootmap_pages(max_low_pfn) << PAGE_SHIFT;
+	bootmap_start = ~0;
+
+	for (i=0; i<sysmem.nr_banks; i++)
+		if (sysmem.bank[i].end - sysmem.bank[i].start >= bootmap_size) {
+			bootmap_start = sysmem.bank[i].start;
+			break;
+		}
+
+	if (bootmap_start == ~0UL)
+		panic("Cannot find %ld bytes for bootmap\n", bootmap_size);
+
+	/* Reserve the bootmem bitmap area */
+
+	mem_reserve(bootmap_start, bootmap_start + bootmap_size, 1);
+	bootmap_size = init_bootmem_node(NODE_DATA(0), min_low_pfn,
+					 bootmap_start >> PAGE_SHIFT,
+					 max_low_pfn);
+
+	/* Add all remaining memory pieces into the bootmem map */
+
+	for (i=0; i<sysmem.nr_banks; i++)
+		free_bootmem(sysmem.bank[i].start,
+			     sysmem.bank[i].end - sysmem.bank[i].start);
+
+}
+
+
+void __init paging_init(void)
+{
+	unsigned long zones_size[MAX_NR_ZONES];
+	int i;
+
+	/* All pages are DMA-able, so we put them all in the DMA zone. */
+
+	zones_size[ZONE_DMA] = max_low_pfn;
+	for (i = 1; i < MAX_NR_ZONES; i++)
+		zones_size[i] = 0;
+
+#ifdef CONFIG_HIGHMEM
+	zones_size[ZONE_HIGHMEM] = max_pfn - max_low_pfn;
+#endif
+
+	/* Initialize the kernel's page tables. */
+
+	memset(swapper_pg_dir, 0, PAGE_SIZE);
+
+	free_area_init(zones_size);
+}
+
+/*
+ * Flush the mmu and reset associated register to default values.
+ */
+
+void __init init_mmu (void)
+{
+	/* Writing zeros to the <t>TLBCFG special registers ensure
+	 * that valid values exist in the register.  For existing
+	 * PGSZID<w> fields, zero selects the first element of the
+	 * page-size array.  For nonexistant PGSZID<w> fields, zero is
+	 * the best value to write.  Also, when changing PGSZID<w>
+	 * fields, the corresponding TLB must be flushed.
+	 */
+	set_itlbcfg_register (0);
+	set_dtlbcfg_register (0);
+	flush_tlb_all ();
+
+	/* Set rasid register to a known value. */
+
+	set_rasid_register (ASID_ALL_RESERVED);
+
+	/* Set PTEVADDR special register to the start of the page
+	 * table, which is in kernel mappable space (ie. not
+	 * statically mapped).  This register's value is undefined on
+	 * reset.
+	 */
+	set_ptevaddr_register (PGTABLE_START);
+}
+
+/*
+ * Initialize memory pages.
+ */
+
+void __init mem_init(void)
+{
+	unsigned long codesize, reservedpages, datasize, initsize;
+	unsigned long highmemsize, tmp, ram;
+
+	max_mapnr = num_physpages = max_low_pfn;
+	high_memory = (void *) __va(max_mapnr << PAGE_SHIFT);
+	highmemsize = 0;
+
+#if CONFIG_HIGHMEM
+#error HIGHGMEM not implemented in init.c
+#endif
+
+	totalram_pages += free_all_bootmem();
+
+	reservedpages = ram = 0;
+	for (tmp = 0; tmp < max_low_pfn; tmp++) {
+		ram++;
+		if (PageReserved(mem_map+tmp))
+			reservedpages++;
+	}
+
+	codesize =  (unsigned long) &_etext - (unsigned long) &_ftext;
+	datasize =  (unsigned long) &_edata - (unsigned long) &_fdata;
+	initsize =  (unsigned long) &__init_end - (unsigned long) &__init_begin;
+
+	printk("Memory: %luk/%luk available (%ldk kernel code, %ldk reserved, "
+	       "%ldk data, %ldk init %ldk highmem)\n",
+	       (unsigned long) nr_free_pages() << (PAGE_SHIFT-10),
+	       ram << (PAGE_SHIFT-10),
+	       codesize >> 10,
+	       reservedpages << (PAGE_SHIFT-10),
+	       datasize >> 10,
+	       initsize >> 10,
+	       highmemsize >> 10);
+}
+
+void
+free_reserved_mem(void *start, void *end)
+{
+	for (; start < end; start += PAGE_SIZE) {
+		ClearPageReserved(virt_to_page(start));
+		set_page_count(virt_to_page(start), 1);
+		free_page((unsigned long)start);
+		totalram_pages++;
+	}
+}
+
+#ifdef CONFIG_BLK_DEV_INITRD
+extern int initrd_is_mapped;
+
+void free_initrd_mem(unsigned long start, unsigned long end)
+{
+	if (initrd_is_mapped) {
+		free_reserved_mem((void*)start, (void*)end);
+		printk ("Freeing initrd memory: %ldk freed\n",(end-start)>>10);
+	}
+}
+#endif
+
+void free_initmem(void)
+{
+	free_reserved_mem(&__init_begin, &__init_end);
+	printk("Freeing unused kernel memory: %dk freed\n",
+	       (&__init_end - &__init_begin) >> 10);
+}
+
+void show_mem(void)
+{
+	int i, free = 0, total = 0, reserved = 0;
+	int shared = 0, cached = 0;
+
+	printk("Mem-info:\n");
+	show_free_areas();
+	printk("Free swap:       %6ldkB\n", nr_swap_pages<<(PAGE_SHIFT-10));
+	i = max_mapnr;
+	while (i-- > 0) {
+		total++;
+		if (PageReserved(mem_map+i))
+			reserved++;
+		else if (PageSwapCache(mem_map+i))
+			cached++;
+		else if (!page_count(mem_map + i))
+			free++;
+		else
+			shared += page_count(mem_map + i) - 1;
+	}
+	printk("%d pages of RAM\n", total);
+	printk("%d reserved pages\n", reserved);
+	printk("%d pages shared\n", shared);
+	printk("%d pages swap cached\n",cached);
+	printk("%d free pages\n", free);
+}
+
+/* ------------------------------------------------------------------------- */
+
+#if (DCACHE_WAY_SIZE > PAGE_SIZE)
+
+/*
+ * With cache aliasing, the page color of the page in kernel space and user
+ * space might mismatch. We temporarily map the page to a different virtual
+ * address with the same color and clear the page there.
+ */
+
+void clear_user_page(void *kaddr, unsigned long vaddr, struct page* page)
+{
+
+  	/*  There shouldn't be any entries for this page. */
+
+	__flush_invalidate_dcache_page_phys(__pa(page_address(page)));
+
+	if (!PAGE_COLOR_EQ(vaddr, kaddr)) {
+		unsigned long v, p;
+
+		/* Temporarily map page to DTLB_WAY_DCACHE_ALIAS0. */
+
+		spin_lock(&tlb_lock);
+
+		p = (unsigned long)pte_val((mk_pte(page,PAGE_KERNEL)));
+		kaddr = (void*)PAGE_COLOR_MAP0(vaddr);
+		v = (unsigned long)kaddr | DTLB_WAY_DCACHE_ALIAS0;
+		__asm__ __volatile__("wdtlb %0,%1; dsync" : :"a" (p), "a" (v));
+
+		clear_page(kaddr);
+
+		spin_unlock(&tlb_lock);
+	} else {
+		clear_page(kaddr);
+	}
+
+	/* We need to make sure that i$ and d$ are coherent. */
+
+	clear_bit(PG_cache_clean, &page->flags);
+}
+
+/*
+ * With cache aliasing, we have to make sure that the page color of the page
+ * in kernel space matches that of the virtual user address before we read
+ * the page. If the page color differ, we create a temporary DTLB entry with
+ * the corrent page color and use this 'temporary' address as the source.
+ * We then use the same approach as in clear_user_page and copy the data
+ * to the kernel space and clear the PG_cache_clean bit to synchronize caches
+ * later.
+ *
+ * Note:
+ * Instead of using another 'way' for the temporary DTLB entry, we could
+ * probably use the same entry that points to the kernel address (after
+ * saving the original value and restoring it when we are done).
+ */
+
+void copy_user_page(void* to, void* from, unsigned long vaddr,
+    		    struct page* to_page)
+{
+	/* There shouldn't be any entries for the new page. */
+
+	__flush_invalidate_dcache_page_phys(__pa(page_address(to_page)));
+
+	spin_lock(&tlb_lock);
+
+	if (!PAGE_COLOR_EQ(vaddr, from)) {
+		unsigned long v, p, t;
+
+		__asm__ __volatile__ ("pdtlb %1,%2; rdtlb1 %0,%1"
+				      : "=a"(p), "=a"(t) : "a"(from));
+		from = (void*)PAGE_COLOR_MAP0(vaddr);
+		v = (unsigned long)from | DTLB_WAY_DCACHE_ALIAS0;
+		__asm__ __volatile__ ("wdtlb %0,%1; dsync" ::"a" (p), "a" (v));
+	}
+
+	if (!PAGE_COLOR_EQ(vaddr, to)) {
+		unsigned long v, p;
+
+		p = (unsigned long)pte_val((mk_pte(to_page,PAGE_KERNEL)));
+		to = (void*)PAGE_COLOR_MAP1(vaddr);
+		v = (unsigned long)to | DTLB_WAY_DCACHE_ALIAS1;
+		__asm__ __volatile__ ("wdtlb %0,%1; dsync" ::"a" (p), "a" (v));
+	}
+	copy_page(to, from);
+
+	spin_unlock(&tlb_lock);
+
+	/* We need to make sure that i$ and d$ are coherent. */
+
+	clear_bit(PG_cache_clean, &to_page->flags);
+}
+
+
+
+/*
+ * Any time the kernel writes to a user page cache page, or it is about to
+ * read from a page cache page this routine is called.
+ *
+ * Note:
+ * The kernel currently only provides one architecture bit in the page
+ * flags that we use for I$/D$ coherency. Maybe, in future, we can
+ * use a sepearte bit for deferred dcache aliasing:
+ * If the page is not mapped yet, we only need to set a flag,
+ * if mapped, we need to invalidate the page.
+ */
+// FIXME: we probably need this for WB caches not only for Page Coloring..
+
+void flush_dcache_page(struct page *page)
+{
+	unsigned long addr = __pa(page_address(page));
+	struct address_space *mapping = page_mapping(page);
+
+	__flush_invalidate_dcache_page_phys(addr);
+
+	if (!test_bit(PG_cache_clean, &page->flags))
+		return;
+
+	/* If this page hasn't been mapped, yet, handle I$/D$ coherency later.*/
+#if 0
+	if (mapping && !mapping_mapped(mapping))
+		clear_bit(PG_cache_clean, &page->flags);
+	else
+#endif
+		__invalidate_icache_page_phys(addr);
+}
+
+void flush_cache_range(struct vm_area_struct* vma, unsigned long s,
+		       unsigned long e)
+{
+	__flush_invalidate_cache_all();
+}
+
+void flush_cache_page(struct vm_area_struct* vma, unsigned long address,
+    		      unsigned long pfn)
+{
+	struct page *page = pfn_to_page(pfn);
+
+	/* Remove any entry for the old mapping. */
+
+	if (current->active_mm == vma->vm_mm) {
+		unsigned long addr = __pa(page_address(page));
+		__flush_invalidate_dcache_page_phys(addr);
+		if ((vma->vm_flags & VM_EXEC) != 0)
+			__invalidate_icache_page_phys(addr);
+	} else {
+		BUG();
+	}
+}
+
+#endif	/* (DCACHE_WAY_SIZE > PAGE_SIZE) */
+
+
+pte_t* pte_alloc_one_kernel (struct mm_struct* mm, unsigned long addr)
+{
+	pte_t* pte = (pte_t*)__get_free_pages(GFP_KERNEL|__GFP_REPEAT, 0);
+	if (likely(pte)) {
+	       	pte_t* ptep = (pte_t*)(pte_val(*pte) + PAGE_OFFSET);
+		int i;
+		for (i = 0; i < 1024; i++, ptep++)
+			pte_clear(mm, addr, ptep);
+	}
+	return pte;
+}
+
+struct page* pte_alloc_one(struct mm_struct *mm, unsigned long addr)
+{
+	struct page *page;
+
+	page = alloc_pages(GFP_KERNEL | __GFP_REPEAT, 0);
+
+	if (likely(page)) {
+		pte_t* ptep = kmap_atomic(page, KM_USER0);
+		int i;
+
+		for (i = 0; i < 1024; i++, ptep++)
+			pte_clear(mm, addr, ptep);
+
+		kunmap_atomic(ptep, KM_USER0);
+	}
+	return page;
+}
+
+
+/*
+ * Handle D$/I$ coherency.
+ *
+ * Note:
+ * We only have one architecture bit for the page flags, so we cannot handle
+ * cache aliasing, yet.
+ */
+
+void
+update_mmu_cache(struct vm_area_struct * vma, unsigned long addr, pte_t pte)
+{
+	unsigned long pfn = pte_pfn(pte);
+	struct page *page;
+	unsigned long vaddr = addr & PAGE_MASK;
+
+	if (!pfn_valid(pfn))
+		return;
+
+	page = pfn_to_page(pfn);
+
+	invalidate_itlb_mapping(addr);
+	invalidate_dtlb_mapping(addr);
+
+	/* We have a new mapping. Use it. */
+
+	write_dtlb_entry(pte, dtlb_probe(addr));
+
+	/* If the processor can execute from this page, synchronize D$/I$. */
+
+	if ((vma->vm_flags & VM_EXEC) != 0) {
+
+		write_itlb_entry(pte, itlb_probe(addr));
+
+		/* Synchronize caches, if not clean. */
+
+		if (!test_and_set_bit(PG_cache_clean, &page->flags)) {
+			__flush_dcache_page(vaddr);
+			__invalidate_icache_page(vaddr);
+		}
+	}
+}
+